1. Field of the Invention
The present invention relates to a drive arrangement for positioning a positioning element with an electric servo motor for driving the positioning element, a potentiometer for setting a setpoint, an actual value sensor disposed at the servo motor, and a motor driver with an integrated evaluation and control unit, which compares the setpoint and actual value. In addition, the invention relates to a method for the electrical control of the movement of a positioning element, particularly of ventilation flaps in motor vehicles, in which a setpoint for controlling an evaluation and control unit containing a motor driver is transmitted and in which an actual value determined at a servo motor is detected in the evaluation unit and compared with the setpoint.
2. Description of the Background Art
Drive arrangements are provided for adjustment and positioning of ventilation flaps in a motor vehicle or used to move positioning elements in control systems or circuits.
A conventional drive arrangement uses stepper motors with gears and/or dc motors with a flange-mounted potentiometer at a gear output or dc gear motors with Hall sensors integrated into the motor. To prevent an inadvertent adjustment of the positioning element by external adjusting effects (in the case of a ventilation flap), for example, by the effect of the air current, in servo drives with a gear the latter is typically made self-locking.
The positioning of the positioning element in the stepper motor occurs by the stepwise driving and counting of the control pulses. In the dc motor provided with a potentiometer, the positioning is made by measuring the potentiometer voltage proportional to the setting angle, as is disclosed and described in DE 197 04 867 C1. The actuation of the dc motors arises with the aid of an adjustment potentiometer in the operating unit.
Difficulties in initiating a control of the servo motor by the adjustment potentiometer can occur when the adjustment potentiometer is changed only by a notch or a minimal amount. In this case, the difference between the setpoint and the actual value can be insufficiently large, so that the setpoint does not exceed the hysteresis of the motor driver and the servo motor is not activated.